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本文主要从X射线的研究,并配合差热分析,测定了1000℃以下的Fe-Ga二元系平衡图。这一系统在室温存在着三个居间相ε,χ和Ψ。ε相是有序面心立方结构,相当于理想化合式Fe3Ga,相区范围很窄。在550℃上下,这个相转变为另一相ξ,这是在高温从Ga在Fe中的固溶体直接分出来的,这个高温相的结构尚未测定。χ相的均匀范围较大,在室温从55at.%Ga延伸到60at.%Ga,结构似乎非常复杂,可能的化合式是Fe4Ga5,Fe3Ga4或Fe2Ga3,这是在960℃上下由包晶反应形成的。Ψ相由另一包晶反应形成,反应温度为820℃,Ψ相属四方晶系,在20℃,α=6.2628?,c=6.5559?,空间群为D4h14-P42/mnm,晶包内含四个化合式量FeGa3。没有观察到Fe在Ga中有任何固溶度。从FeGa3到Ga,存在着一条共晶等温线,共晶点非常接近纯Ga,在约590℃,存在着一条共析等温线,共析点在50at.%Ga左右,在这里Ga在Fe中的固溶体同时分解成ξ和χ。这个系统中最值得注意的是Ga在Fe中的原生固溶体。在室温的固溶度是15.2at.%,它随温度而逐渐递增,在700℃以上,则突增到约50at.%,在625℃以下的结构是体心立方体,在相图中用α代表。但在625℃以上,这个相又转变为两个不同的结构,并且各占据着一定的相域,在相图中各用α1和α2代表。α1和α2的结构尚未经测定,最可能是从α结构导生的、由基本单胞依照一定规律堆垜起来而产生的原子的重新排列或空位缺陷。The equilibrium diagram of the Fe-Ga system below 1000℃ has been determined mainly by X-ray investigation incorporated with differential thermal analysis. The system consists at room temperature of three intermediate phases ε, χ, and ψ. The ε phase with a very narrow homogeneous range has an ordered face-centred structure corresponding to the ideal formula Fe3Ga. At about 550℃, it transforms into another phase ζ which separates at higher temperature directly from the solid solution of Ga in Fe. The structure of the high temperature phase ζ has not been determined. The homogeneous range of the χ phase extends at room temperature from 55 at. % Ga to 60 at. % Ga. The structure of this phase appears to be very complicated, presumably corresponding to the structural formula Fe4Ga5, Fe3Ga4 or Fe2Ga3. It is formed at about 960℃ by a peritectic reaction. The ψ phase is formed by another peritectic reaction at 820℃. The structure is tetragonal, with a=6.2628? and c=6.5559? at 20℃. The space group is D4h14-P42/mnm, and each unit cell contains four formula units corresponding to FeGa3. No noticeable solubility of Fe in Ga has been observed. There exists an eutectic isothermal ranging from FeGa3 to Ga, the eutectic point being very near to the pure component. There exists also an eutectoid isothermal at about 590℃, the eutectoid point being approximately at 50 at. % Ga, at which the solid solution of Ga in Fe decomposes simultaneously into ζ and χ. The most remarkable feature of this system is the primary solid solution region of Ga in Fe. The solubility at room temperature is 15.2 at. %. It gradually increases with temperature, and above 700℃, it increases suddenly up even to 50 at. %. The structure below 625℃ is body-centred cubic, designated as a in the phase diagram. But above 625℃, it changes into two other structures with their respective phase regions, designated as α1 and α2. The structures of α1 and α2 have not been elucidated yet, but most probably they are derived from a by stacking together the fundamental unit cells with atomic rearrangement or vacancy defect.
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